Current handheld diagnostic systems require a significant power supply to move fluids around the chip. Microfluidic assay systems are frequently, at least partly, pneumatically-driven. A pump is connected to a microfluidic circuit and energized to move fluid through a microfluidic circuit. Valves may be provided externally to control the flow. Micropumps of suitable design for assay devices are relatively large and use a power source.
Microfluidic assay systems have employed magnetic beads with surfaces with probes to combine with target biomolecules or cells are trapped in a flow passage by a magnet. The beads are combined with a solution containing the target biomolecules or cells and the combination flowed through the chamber such that the magnetic beads remain in the chamber.